1. Field of the Invention
The present invention relates generally to semiconductor processing and, more particularly, to the formation of a metal silicide layers.
2. Description of Related Art
A known method of forming a metal silicide layer on polysilicon comprises depositing a metal layer on the polysilicon, performing a first rapid thermal processing (RTP) step, performing a wet etch, and then performing a second RTP step.
When a layer of polysilicon has a non-planar topography, using conventional physical vapor deposition (PVD) to deposit the metal layer can result in poor bottom coverage, meaning that either the metal layer is not deposited onto the low points of the topography or the metal layer that may exist at those low points is thin compared to the metal layer deposited onto the higher points of the topography. Likewise, to the extent a metal deposition process were to be accomplished through ionized metal plasma physical vapor deposition (IMP PVD) with a biased wafer chuck, the bottom coverage may be exceptional, but the sidewall coverage may be poor.
A need thus exists in the prior art to deposit a metal silicide layer onto patterned polysilicon such that the metal silicide thickness is relatively uniform over the tops, sides, and bottoms of the non-planar topography polysilicon. A relatively uniform metal silicide layer over non-planar topography polysilicon may be desired to provide, for example, enhanced device performance and reliability.